function Bomb(){
    var id;
    this.start=function(){
        id=setTimeout(function(){
            console.log('炸弹爆炸');
        },3000);
    };
    this.clear=function(){
        clearTimeout(id);
    }
}
var b1=new Bomb();
var b2=new Bomb();
b1.start();
b2.start();
setTimeout(b2.clear,1000);